Interference canceling by fixed division of feeder link transmission band in multiple gateway HAPS system

A relay communication station incorporated in an aerial-staying type communication relay apparatus to relay a radio communication of a terminal apparatus, the relay communication station comprising:

• a feeder-link communication section that transmits and receives relay signals different from each other on a same frequency in feeder links between the feeder-link communication section and plural gateway stations that are time-synchronized with each other;
• and
• an interference suppression section that suppresses interferences between plural feeder links formed with the plural gateway stations and the interference suppression section, and
• wherein the feeder-link communication section receives pilot signals respectively transmitted from the plural gateway stations, and separates each of the received plural pilot signals with a filter, and
• wherein the interference suppression section:
• divides a transmission signal band of the feeder link into plural divided frequency bands, and estimates plural propagation path responses respectively between the plural gateway stations and an antenna for feeder link of the communication relay apparatus with respect to each of the plural divided frequency bands, by setting a center frequency of each of the plural divided frequency bands as an estimation frequency, based on a reception result of the pilot signals respectively received from the plural gateway stations and separated from each other;
• calculates, for each of the divided frequency bands with respect to each of the plural gateway stations, a weight for suppressing an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, based on the plural propagation path responses;
• and
• subtracts, for each of the divided frequency bands with respect to each of the plural gateway stations, a reception signal received with the directional beam corresponding to the other gateway station and multiplied by the weight corresponding to the other gateway station, from the reception signal received by the directional beam corresponding to the other gateway station.

A feeder-link interference suppression method in a relay communication station that is incorporated in an aerial-staying type communication relay apparatus and relays a radio communication of a terminal apparatus, the feeder-link interference suppression method comprising:

• receiving pilot signals respectively transmitted from plural gateway stations that are time-synchronized with each other;
• separating each of the received plural pilot signals with a filter;
• dividing a transmission signal band of the feeder link into plural divided frequency bands, and estimating plural propagation path responses respectively between the plural gateway stations and an antenna for feeder link of the communication relay apparatus with respect to each of the plural divided frequency bands, by setting a center frequency of each of the plural divided frequency bands as an estimation frequency, based on a reception result of the pilot signals respectively received from the plural gateway stations and separated from each other;
• calculating, for each of the divided frequency bands with respect to each of the plural gateway stations, a weight for suppressing an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, based on the plural propagation path responses;
• and
• subtracting, for each of the divided frequency bands with respect to each of the plural gateway stations, a reception signal received with the directional beam corresponding to the other gateway station and multiplied by the weight corresponding to the other gateway station, from the reception signal received by the directional beam corresponding to the other gateway station.

A non-transitory computer readable medium containing software that is executed by a computer or a processor installed in a relay communication station that is incorporated in an aerial-staying type communication relay apparatus and relays a radio communication of a terminal apparatus, the software comprising:

• executable code that transmits and receives relay signals different from each other on a same frequency in a feeder link between the relay communication station and plural gateway stations that are time-synchronized with each other;
• executable code that receives pilot signals respectively transmitted from the plural gateway stations;
• executable code that separates each of the received plural pilot signals with a filter;
• executable code that divides a transmission signal band of the feeder link into plural divided frequency bands, and estimates plural propagation path responses respectively between the plural gateway stations and an antenna for feeder link of the communication relay apparatus with respect to each of the plural divided frequency bands, by setting a center frequency of each of the plural divided frequency bands as an estimation frequency, based on a reception result of the pilot signals respectively received from the plural gateway stations and separated from each other;
• executable code that calculates, for each of the divided frequency bands with respect to each of the plural gateway stations, a weight for suppressing an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, based on the plural propagation path responses;
• and
• executable code that subtracts, for each of the divided frequency bands with respect to each of the plural gateway stations, a reception signal received with the directional beam corresponding to the other gateway station and multiplied by the weight corresponding to the other gateway station, from the reception signal received by the directional beam corresponding to the other gateway station.